Central Dogma of Molecular Genetics Restriction-Modification Systems of Bacteria Cloning Vectors cDNA Cloning Clone Library Screening DNA Sequencing Southern and Northern Analysis Exons and Introns Polymerase Chain Reaction (or PCR) Study Questions Cloning and Molecular Analysis of Genes WWW Links Genetic Topics

cDNA Cloning The cloning that has been described here will work for any random piece of DNA. But since the goal of many cloning experiments is to obtain a sequence of DNA that directs the production of a specific protein, any procedure that optimizes cloning will be beneficial. One such technique is cDNA cloning. The principle behind this technique is that an mRNA population isolated from a specific developmental stage should contain mRNAs specific for any protein expressed during that stage. Thus, if the mRNA can be isolated, the gene can be studied. mRNA cannot be cloned directly, but a DNA a copy of the mRNA can be cloned. (In this regard, the term cDNA is short for "copy DNA".) This conversion is accomplished by the action of reverse transcriptase and DNA polymerase. The reverse transcriptase makes a single-stranded DNA copy of the mRNA. The second DNA strand is generated by DNA polymerase and the double- stranded product is introduced into an appropriate plasmid or lambda vector. Copyright © 1997. Phillip McClean